Mechanism for crowning gears



Jan. 8, 1963 w. H. PICKENER MECHANISM FOR CROWNING GEARS Filed May 1, 1961 2 Sheets-Sheet 1 INVENTOR.

WALTER H. PICKENER H|5 ATTORNEY w. H. PICKENER 3,071,897

MECHANISM FOR CROWNING GEARS Jan. 8, 1963 2 Sheets-Sheet 2 Filed May 1, 1961 m m MK T P T IHH .A h v 5 m H m W Y B w 8 5 ,7 3 3 y H FIEZ United States Patent Office 3,071,897 Patented Jan.'8, 1963 3,071,897 MECHANISM FOR CROWNING GEARS Walter H. Pickener, Ludlow, Vt., assignor to The Fellows Gear Shaper Company, Springfield, Vt, a corporation of Vermont Filed May 1, 1961, Ser. No. 106,607 Claims. (Cl. 51-95) The present invention relates to gear finishing machines such as gear grinding machines and the like and is more particularly directed to a new and improved apparatus for crowning gears while they are in the process of being ground.

The machine of the present invention is used in conjunction with a grinding worm or drum in which a grinding thread is formed on the circumference and this thread has a helical lead thereon. This tool is rapidly rotated in mesh with the gear being finished. As will be apparent to one skilled in the art, a tool which is of the so-called shaving type may also be employed as a finishing tool, and in this type of tool the forming thread is provided with lands and grooves on the face of the thread. Other tools and their use herewith will be obvious to those skilled in the art.

As the work is rotated in mesh with the finishing tool the work is fed axially. In order to obtain this action the work piece is mounted on a reciprocable work slide adjacent to the finishing worm periphery with the axis of -the work at right angles or substantially so to the grinding worm axis. If helical gears are being finished obviously the axis will be at some angle other than right angles to the axis of the finishing worm. As the work is rotated in mesh with the tool the work slide is reciprocated up and down in the direction of the work axis while the teeth of the work piece are rotated in mesh with the threads of the rotating grinding worm.

A machine of the type herein concerned and to which the present invention is applied is shown in US. Patent No. 2,786,309 entitled Gear Grinding Machine and which issued on March 26, 1957, to Alfred Rickenmann.

It is a principal object of the present invention to provide a device of the character described in which a crowning effect can be produced on gears being ground in a fast and efiicient manner.

Another object of the present invention is to provide a device for crowning gears in which the forming occurs on both strokes of the work in each direction while the gear being ground traverses the grinding or finishing wheel.

Another object of the present invention is to provide a device for crowning gears in which a crowning effect may be produced on both sides of the teeth of a work gear during a single grinding traverse.

Another object of the present invention is to provide a device of the character described herein for crowning gears in which a crowning effect can be produced without employing a special contour on the finishing or grinding tool.

Another object of the present invention is to provide a device of the character described for crowning gears in which many varied crowning effects may be obtained by a simple and minor mechanical operation.

Still another object is to provide a simple device in which a pivotal movement is imposed on the work by locating the fulcrum of the pivotal movement in a desired location with respect to the work and the crowning is obtained on the work by pivoting it in only a single direction, thus greatly simplifying the apparatus and making it possible to obtain greater accuracy therewith.

In order to obtain this result the fulcrum is spaced from the radial plane of the finishing tool which penetrates the work gear to the greatest depth.

In the drawings:

FIGURE 1 is a front elevation view of a grinding machine of the type in which the present invention is used in conjunction therewith and illustrating the grinding carriage and grinding worm relative to the gear being ground.

FIGURE 2 is an end view of the machine showing the support and rotatable drum which carries the work slide and illustrating the crowning mechanism attached thereto.

FIGURE 3 is a cross sectional view taken along line 33 of FIGURE 2 showing the crowning cam, its mounting cam, its mounting and the gear drivemeans connected therewith.

FIGURE 4 is a cross sectional view taken along line 4-4 of FIGURE 2 showing the construction of the pivot pin and two rollers.

Like reference characters designate the same parts wherever they occur in the specification and all the drawmgs.

The machine consists of a base 1 on which a grinding carriage 2 is mounted. The grinding worm C is mounted on and fixed to a shaft or spindle 3. Spindle 3 is rotated by any well known means (not shown) and is geared to rotate in timed relation with the remaining elements of the machine.

Base 1 has a work support 4; mounted on its end opposite to that on which carriage 2 is mounted. Work support 4 houses a rotatably adjustable drum 5. The forward portion of drum 5 has a work slide 6 mounted thereon. Work slide 6 has mounted thereon a tailstock 7 and headstock 8 between which a work arbor 9 sup ports the gear W which is to be ground.

Work slide 6 is slideably moved during the grinding of gear W so that gear W makes reciprocation passes relative to grinding worm C at which time the teeth of gear W mesh with the helical rib of rotating worm C.

The manner in which work slide 6 is shifted can be of any well known mechanical or hydraulic means and is not shown in the drawings herewith since the means of shifting is not pertinent to or part of the present invention. The details of the structure referred to above are counterparts of similar elements shown and described in Rickenmann.

Work support 4 is mounted on base 1. A gib 10 is fixed to base 1 by bolts 11. Gib 10 contains springs 12 which are seated in recessed portions provided in gib 10. Springs 12 also abut against a flat provided on support 4 for a purpose as set forth below.

A fulcrum point for work support 4 is the half round fulcrum 13 bolted to support 4 by bolt 14. Half round fulcrum 13 rides in a V slot in base 1.

A rack 55 which corresponds to rack 55 of the above mentioned patent is provided on the side of'work slide 6 and as shown in FIGURE 1 is in mesh with a pinion 54. Pinion 54 is mounted on the end of shaft 53. The other end of shaft 53 has a gear 52 mounted thereon and held in place by a nut 51. Shaft 53 has an extension portion 15 on which a gear 16 is mounted. The end of extension shaft 15 is journaled in a bearing 17 which is housed in support cover 18. A rotatable shaft 19 is also mounted in a bearing 20 in support cover 18.

Shaft 19 has a gear 21 mounted on one end which meshes with gear 16 and which is obviously driven by the rotation of shaft 53 and gear 16. On the outer end of shaft 19 a cam 22 is held thereon by a nut 23.

The periphery of cam 22 is eccentric and it may be called the crowning cam. 1

Crowning cam 22 abuts against a roller 24 which is mounted on a shaft 25 of arm 26. An adjustment bolt 27 threads through arm 26 and shaft 25. The end of bolt 27 abuts against the outside of spindle support cover 18. The bolt 27 is rotated to remove contact of the roller 24 from the crowning cam 22. As the bolt 27 is fed in it will be obvious that the roller 24 is removed from con.- tact with the cam thereby permitting the removal of the cam 22 from the shaft 19. The cam may then be removed and a new cam substituted therefor or else the machine may be operated without the use of the crowning attachment.

On the lower portion of work support 4 is mounted a bracket member 28 which is held thereon by means of bolts 29.

Bracket member 28 carries the arm 26 pivotaliy mounted thereon by means of pivot pin 39. Arm as carries a lower roller 31 mounted adjacent to pivot pin 30. Roller 3 1 is mounted on a roller pin 32. Another roller 33 is eccentrically mounted on a pin 34 in bracket member 28.

Base 1 has a rail carrying bracket member 35 mounted to it by bolts 3s.

Bracket member 35 has a rail 37 mounted on its topmost portion underneath rollers 31 and 33. Rail 37 is held on bracket 35 by bolts 38.

Springs 12 serve to keep the roller 24 against cam 22 by the springs exerting pressure downward and thus the pivot pin is also forced downward and holds lower roller 3-1 against rail 37 and pivots arm 26 around pivot pin 36 and keeps roll 24 against cam 22.,

When work slide 6 recipr-ocates the rack 55 causes pinion 54 to rotate shaft 53 and gear 16. Gear 16 rotates gear 21 and cam 22. Cam 22 rotates against roller 24- and moves arm 25 which is pivoted at pin 39. The movement of arm 26 causes roller 3-1 to bear down on rail 37 of bracket which is held fast to base 1, thus lifting work support 4 off base 1 at the rear end. When this occurs work support 4 pivots at its fulcrum point on half round fulcrum 13 at its front portion.

By the proper disposition of the outer periphery of crowning cam 22 the gradual lifting of support 4 occurs until cam 22 reaches its high point at a time when work W is at the top or bottom of its passing grinding stroke as it traverses by grinding wheel C. Work W is gradually tipped at the desired angle whereby more stock is ground off each side of the particular tooth being ground thus leaving a crowned effect on said tooth.

During the gradual lowering of support 4*, cam 22 reaches its low point as shown at a time when work W is at the center of its traversing by grinding wheel C.

Eccentric roller 33 mounted on bracket 28 can be rotated to bear down on rail 37 and stabilize the weight of work support 4 when it is desired to grind gears without crowning,

Crowning cam 22 may be of different configurations and may be easily changed to effect different types of crowning on different gears being ground.

Springs 12 exert pressure downward on the support 4 as previously described and until support 4 contacts base 1, the springs hold arm 26 and roll 24 against cam 22.

When crowning cam 22 rotates back to its normal low point against roller 24 the arm 26 has moved back to its normal position, and the roller 31 is not effecting leverage against rail 37 and support 4 has returned to its normal resting place on base 1.

It will be apparent to those skilled in the art that hitherto in crown grinding of gears the tilting of the work or tool in order to remove additional material from both the top and bottom of a particular gear being finished necessitated oscillating the work or tool first one way and then the other.

In the present invention one aspect of novelty of the mechanism lies in the fact that because of the location of the fulcrum point between the base and the work support the work W tilts in only one direction therefore greatly simplifying the mechanism and crowning action.

As will be apparent when work W starts an upward grinding pass from its mid part against the grinding wheel C the work W is gradually tilted because of the configura- 'tion of cam 22. As work W travels in an upward direction a crowning effect is obtained on the bottom half portion of its tooth then cam 22 returns to its low portion as seen in FIGURE 2 and work W is in the position relative to grinding worm C as shown in FIGURE 1. Work W then travels downward and cam 22 approaches its other high point, again work W is tilted in the same direction to effect a similar crowning on the top half of the tooth being ground. When work W reaches the bottom of its grinding traverse against grinding wheel C the work slide 6 starts its return upward stroke. At this time cam 22 again returns to its low point and work W returns to the position as shown in FIGURE 1.

It will readily be apparent that as stated above many different crowning results may be obtained with the present apparatus by varying the cam 22 and its rotation relative to the reciprocation of the work past the grinding wheel. Also by pivoting the work in the same direction about its fulcrum (counterclockwise as seen in FiGURE l) a greatly simplified structure and control is obtained. it is possible with this arrangement to definitely locate the work support 4 against the base 1 while the central portion of the work gear is being ground.

What I claim and desire to secure by Letters Patent is:

1. In a machine of the character described, a base, a gear finishing tool mounted for rotation on said base, a work support mounted on said base, a fulcrum on which said work support is pivotally mounted on said base, a work carrying slide reciprocably mounted on said work support, means on said work carrying slide to hold a work gear in engagement with said finishing tool, means to pivot said work support about said fulcrum, said last named means including a shaft rotatably mounted in said work support a crowning cam mounted on said shaft to oscillate on said work support, a geared connection between said reciprocable work carrying slide and said cam whereby said cam is oscillated in timed relation to the movement of said slide, and means coacting between said cam and said base to rotate said work support about its fulcrum to vary the distance between said finishing tool and the work gear so as to crown said work gear as it is reciprocated in engagement with said finishing tool.

2. In a machine of the character described, a base, a gear finishing tool mounted for rotation on said base, a work support mo-unted'on said base, a fulcrum on which said work support is pivotally mounted on said base, a work carrying slide reciprocably mounted on said work support, means on said work carrying slide to hold a work gear in engagement with said finishing tool, means to pivot said work support about said fulcrum, said last named means including a shaft rotatably mounted in said work support a crowning cam mounted on said shaft to oscillate on said work support, a geared connection between said reciprocable work carrying slide and said cam whereby said cam is oscillated in timed relation to the movement of said slide, a lever pivoted on said Work support, bearing means on said lever contacting said crowning cam, a second means on said lever abutting said base whereby when said lever is pivoted by the contact of said crowning cam and said bearing means said support will be rotated about its fulcrum so as to crown said work gear as it is traversed past said finishing tool.

3. In a machine of the character described, a base, a gear finishing tool mounted for rotation on said base, a work support mounted on said base, a fulcrum on which said work support is pivotally mounted on said base, a work carrying slide reciprocably mounted on said work support, means on said work carrying slide to hold a work gear in engagement with said finishing tool, means to pivot said work support about said fulcrum, said last named means including a shaft rotatably mounted in said work support, gearing connecting said work carrying slide and said shaft so that said shaft is rotated in accordance with the movement of said slide and a crowning cam mounted on said shaft to oscillate on said work support in timed relation to the movement of said slide, a lever pivoted on said work support, bearing means on said lever contacting said crowning cam, a rail fixed to said base, and means on said lever bearing on said rail whereby as said lever is pivoted due to contact between said bearing means and said cam said support will be lifted from its contact with said base and rotated about said fulcrum so as to crown said work gear as it is traversed past said finishing tool.

4. In a machine of the character described, a base, a gear finishing tool mounted for rotation on said base, a work support mounted on said base adjacent to said finishing tool, said work support having a pivotal mounting on said base, a work carrying slide reciprocable on said support, means on said slide to hold a work gear in position to be engaged by said finishing tool, said pivotal mounting of said support being spaced from the radial plane of said tool having the greatest depth of penetration with said work gear and means to rotate said support in the same given direction about said pivotal mounting as said slide is reciprocated whereby said work gear is fed into greater depth relative to said finishing tool on both ends thereof while said work slide is traversed past said tool so as to crown both ends of the teeth of said work gear, said last named means including a shaft rotatably mounted in said work support, gearing connecting said work carrying slide and said shaft so that said shaft is rotated in accordance with the movement of said slide, a crowning cam connected to said shaft and rotatable in timed relation to the movement of said slide and means coacting between said cam and the base of said machine to move said support about its pivotal mounting.

5. A device of the character set forth in claim 4 in which said last named means includes a rail member fixed to said base and a lever fixed pivotally to said support in contact with said cam and said rail member whereby said support is moved about its pivotal mounting by movement of said crowning cam against said lever.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A MACHINE OF THE CHARACTER DESCRIBED, A BASE, A GEAR FINISHING TOOL MOUNTED FOR ROTATION ON SAID BASE, A WORK SUPPORT MOUNTED ON SAID BASE, A FULCRUM ON WHICH SAID WORK SUPPORT IS PIVOTALLY MOUNTED ON SAID BASE, A WORK CARRYING SLIDE RECIPROCABLY MOUNTED ON SAID WORK SUPPORT, MEANS ON SAID WORK CARRYING SLIDE TO HOLD A WORK GEAR IN ENGAGEMENT WITH SAID FINISHING TOOL, MEANS TO PIVOT SAID WORK SUPPORT ABOUT SAID FULCRUM, SAID LAST NAMED MEANS INCLUDING A SHAFT ROTATABLY MOUNTED IN SAID WORK SUPPORT A CROWNING CAM MOUNTED ON SAID SHAFT TO OSCILLATE ON SAID WORK SUPPORT, A GEARED CONNECTION BETWEEN SAID RECIPROCABLE WORK CARRYING SLIDE AND SAID CAM WHEREBY SAID CAM IS OSCILLATED IN TIMED RELATION TO THE MOVEMENT OF SAID SLIDE, AND MEANS COACTING BETWEEN SAID CAM AND SAID BASE TO ROTATE SAID WORK SUPPORT ABOUT ITS FULCRUM TO VARY THE DISTANCE BETWEEN SAID FINISHING TOOL AND THE WORK GEAR SO AS TO CROWN SAID WORK GEAR AS IT IS RECIPROCATED IN ENGAGEMENT WITH SAID FINISHING TOOL. 